JP5123782B2 - Base station and mobile communication method - Google Patents

Description

  The present invention relates to a base station and a mobile communication method.

  In recent years, base stations that can be freely installed by users have been developed, and are called “femto base stations” in contrast to macro base stations that are installed, designed, and operated by communication operators.

  In the femto base station, it is considered to perform “user limitation” that only the owning user can occupy and use the femto base station. In such a case, only a pre-registered mobile device (femto mobile device) can perform communication using such a femto base station.

  Hereinafter, a base station that is operated by a telecommunications carrier and provides public communication services is referred to as a “macro base station”, and a mobile station that performs communication using the macro base station is referred to as a “macro mobile station” and is installed by a user Such a base station is referred to as a “femto base station”, and a mobile device registered in the femto base station and performing communication using the femto base station is referred to as a “femto mobile device”.

  When the “user only” is performed at the femto base station, the macro base station does not communicate with the femto base station even if the macro mobile station that communicates with the macro base station exists in the vicinity of the femto base station. A situation may occur where communication is performed. For example, the situation is such that a macro mobile device communicates with a macro base station installed outdoors, indoors where a femto base station is installed.

  Usually, in such a situation, since the macro mobile station performs handover to the femto base station and performs transmission power control in accordance with the femto base station, the femto base station does not receive large uplink interference.

  However, when “user limitation” is performed in the femto base station, the macro mobile station cannot communicate with the femto base station, and therefore communicates with the macro base station.

  Here, the macro mobile station performs transmission with large transmission power to a macro base station that is located farther than the femto base station, and the femto base that is installed in the vicinity of the macro base station. There is a risk of causing large uplink interference to the base station.

  Due to such uplink interference, the communication quality between the femto base station and the femto mobile device may be deteriorated or communication may not be possible. In order to solve such a problem, a method has been proposed in which the reception sensitivity in the femto base station is lowered to maintain the uplink communication quality.

  On the other hand, there is concern about the interference that the transmission power at the femto base station gives to the macro base station, and when interference is given to the macro base station, the transmission power at the femto base station is reduced to cause interference. A way to avoid this is considered.

In this case, since the downlink cell radius is narrowed, the reception sensitivity at the femto base station may be decreased in order to narrow the uplink cell radius.
Japanese Patent Application Laid-Open No. 9-191311

  As described above, in the femto base station, the reception sensitivity may be changed. However, since the reception sensitivity is decreased, the femto mobile station (registered mobile station) that is not detected in the femto base station even if transmission is performed with the maximum transmission power. May occur.

  For example, even though a femto mobile station (registered mobile station) is sending a call request indoors where the femto base station is installed, the reception sensitivity of the femto base station is low. There is a possibility that the femto base station cannot sense the transmission request from the femto mobile station.

  Accordingly, the present invention has been made in view of the above-described problems, and a base station and a mobile communication method capable of detecting a signal from a registered mobile device even when the reception sensitivity in the base station is reduced. The purpose is to provide.

  A first feature of the present invention is a base station, which is transmitted via an uplink, with a registered mobile device management unit configured to manage one or more mobile devices as registered mobile devices. A reception sensitivity control unit configured to determine a reception sensitivity for a signal, and a paging signal transmission unit configured to transmit a paging signal to the registered mobile station, for a predetermined period, The reception sensitivity control unit is configured to increase the reception sensitivity when the signal from the registered mobile device is not detected, and the paging signal transmission unit is configured to transmit a paging signal to the registered mobile device. The reception sensitivity control unit is configured to determine the reception sensitivity based on the presence / absence of a response to the paging signal from the registered mobile device.

  A second feature of the present invention is a mobile communication method in which one or a plurality of mobile devices are managed as registered mobile devices, and a signal from the registered mobile device is detected for a predetermined period in a base station. If not, based on the step B of increasing the reception sensitivity for the signal transmitted via the uplink and transmitting a paging signal to the registered mobile device and the presence or absence of a response to the paging signal from the registered mobile device And the step C of determining the reception sensitivity.

  As described above, according to the present invention, it is possible to provide a base station and a mobile communication method capable of detecting a signal from a registered mobile device even when reception sensitivity at the base station is reduced. .

(Configuration of base station according to the first embodiment of the present invention)
With reference to FIG.1 and FIG.2, the structure of the base station which concerns on the 1st Embodiment of this invention is demonstrated. Hereinafter, the configuration of the femto base station 1 will be described as the configuration of the base station according to the first embodiment of the present invention, but the present invention is also applicable to base stations other than the femto base station 1.

  The femto base station 1 according to the present embodiment can be used not only in a W-CDMA mobile communication system but also in a LTE (Long Term Evolution) mobile communication system, for example.

  As shown in FIG. 1, the femto base station 1 according to the present embodiment includes a registered mobile station database (DB) 11, a reception unit 12, a signal demodulation unit 13, a reception sensitivity control unit 14, and a determination unit 15. The signal generator 16 and the transmitter 17 are provided.

  The registered mobile device DB 11 is configured to manage one or more mobile devices as registered mobile devices. Here, it is assumed that only registered mobile devices can communicate using the femto base station 1.

  The owner of the femto base station 1 may register the registered mobile device with a network device (for example, an exchange MSC / MME / SGSN or a radio network controller RNC), or the registered mobile device of the femto base station 1. You may register directly in DB11.

  When a registered mobile device is registered in a network device, the femto base station 1 is configured to acquire information related to the registered mobile device from the network device and register it in the registered mobile device DB 11. .

  The reception unit 12 is configured to perform reception processing on a signal transmitted from a registered mobile device via an uplink with the reception sensitivity determined by the reception sensitivity control unit 14.

  The signal demodulator 13 is configured to perform demodulation processing on the signal received by the receiver 12.

  The reception sensitivity control unit 14 is configured to determine the reception sensitivity for the signal transmitted via the uplink and notify the reception unit 12 of the determined reception sensitivity.

  Specifically, the reception sensitivity control unit 14 may be configured to increase the reception sensitivity when a signal from the registered mobile device is not detected for a predetermined period. More specifically, the reception sensitivity control unit 14 sets the reception sensitivity when the reception sensitivity is “S0 (first reception sensitivity)” and when a signal from the registered mobile device is not detected for a predetermined period. You may be comprised so that it may raise to "S1 (2nd receiving sensitivity)." Here, it is assumed that “S1” has higher reception sensitivity than “S0”.

  The reception sensitivity control unit 14 may be configured to determine the reception sensitivity based on the presence / absence of a response to the paging signal from the registered mobile device.

  For example, the reception sensitivity control unit 14 sets the reception sensitivity to “S1” when the above response is received, and sets the reception sensitivity to “S0” when the above response is not received.

  The determination unit 15 is configured to determine whether or not a paging signal should be transmitted to the registered mobile device in order to confirm the presence of the registered mobile device.

  Specifically, the determination unit 15 determines that a paging signal should be transmitted to the registered mobile device when a signal from the registered mobile device is not detected for a predetermined period, and the signal creation unit 16 It may be configured to instruct. More specifically, the determination unit 15 transmits a paging signal to the registered mobile device when the reception sensitivity is “S0” and a signal from the registered mobile device is not detected for a predetermined period. It may be configured to determine that it should be, and to instruct the signal creation unit 16 to that effect.

  The signal generator 16 is configured to generate a paging signal for the registered mobile device in response to an instruction from the determination unit 15.

  The transmission unit 17 is configured to transmit the paging signal created by the signal creation unit 16 to the registered mobile device. Here, the transmission unit 17 is configured to transmit a paging signal so as to reach the entire service area of the femto base station 1.

(Operation of the base station according to the first embodiment of the present invention)
With reference to FIG. 2, the operation of the femto base station 1 according to the first embodiment of the present invention will be described.

  As shown in FIG. 2, in step S100, the femto base station 1 is in a state where the reception sensitivity is set to “S0”. For example, the femto base station 1 is in a state where the reception sensitivity is set to “S0” in order to withstand uplink interference or to narrow the radius of the uplink area. Further, it is assumed that the femto base station 1 manages registered mobile devices in advance.

  In step S101, the femto base station 1 determines whether or not the timer has expired without receiving a signal from the registered mobile device as to whether or not uplink communication from the registered mobile device has been interrupted for a predetermined period. When it is determined that the operation is interrupted, the operation proceeds to step S102. When it is determined that the operation is not interrupted, the operation repeats step S101.

  In step S102, the femto base station 1 determines whether there is room for increasing the reception sensitivity. When it is determined that there is room, the operation proceeds to step S103, and when it is determined that there is no room, the operation proceeds to step S107.

  In step S103, the femto base station 1 increases the reception sensitivity to “S1”, and in step S104, the femto base station 1 transmits a paging signal to the registered mobile device with predetermined transmission power.

  In step S105, the femto base station 1 determines whether or not a response to the paging signal from the registered mobile device has been received. When it is determined that it has been received, this operation proceeds to step S106, and when it is determined that it has not been received, this operation proceeds to step S107.

  In step S106, the femto base station 1 determines that the signal from the registered mobile station existing in the service area cannot be detected with the current reception sensitivity “S0”, and sets the reception sensitivity to “S1”.

  On the other hand, in step S107, the femto base station 1 determines that there is no registered mobile station in the service area or that there is no room for increasing the reception sensitivity, and does not change the reception sensitivity from “S0” and sets the timer. set.

(Operations and effects of the base station according to the first embodiment of the present invention)
According to the base station according to the first embodiment of the present invention, the reception sensitivity is periodically lowered and the registration mobile station is called (transmitting a paging signal), thereby registering because the reception sensitivity is too low. It is possible to avoid a situation in which communication with the mobile device becomes impossible.

  Furthermore, according to the base station according to the first embodiment of the present invention, the optimum parameter can be automatically set based on the reception sensitivity when the registered mobile station responds to the above-mentioned call.

  That is, according to the base station according to the first embodiment of the present invention, even when “user limitation” is performed, reception sensitivity and transmission power are set appropriately, and communication service quality is improved. be able to.

(Modification 1)
With reference to FIGS. 3 to 5, a first modification of the first embodiment of the present invention will be described. Hereinafter, the femto base station 1 according to the first modification will be described by focusing on differences from the femto base station 1 according to the first embodiment described above.

  As shown in FIG. 3, in addition to the configuration of the femto base station 1 according to the first embodiment, the femto base station 1 according to the first modification includes a correspondence notation unit 18 and a transmission power control unit 19. It has.

  As shown in FIG. 4, the correspondence table storage unit 18 is configured to store a correspondence table that associates “reception sensitivity” with “transmission power of a paging signal”.

  The transmission power control unit 19 is configured to determine the transmission power of the paging signal to be transmitted to the registered mobile device in response to an instruction from the determination unit 15. For example, the transmission power control unit 19 refers to the correspondence table stored in the correspondence table storage unit 18, and transmits the transmission power corresponding to the reception sensitivity raised by the reception sensitivity control unit 14 to the registered mobile device. You may be comprised so that it may be set as the transmission power of the paging signal to transmit.

  The transmission power control unit 19 is configured to determine the transmission power of a signal to be transmitted via the downlink based on the presence / absence of a response to the paging signal from the registered mobile device.

  Specifically, when receiving a response to the paging signal from the registered mobile device, the transmission power control unit 19 sets the transmission power of the paging signal (or the transmission power corresponding to the transmission power of the paging signal) to the downlink. You may be comprised so that it may be set as the transmission power of the signal transmitted via a link.

  The transmission unit 17 is configured to transmit an arbitrary signal including a paging signal to the registered mobile device with the transmission power determined by the transmission power control unit 19.

  With reference to FIG. 5, the operation of the femto base station 1 according to the first embodiment of the present invention will be described.

  As shown in FIG. 5, in step S200, the femto base station 1 is in a state where the reception sensitivity is set to “Sm (0 ≦ m ≦ n)”. For example, the femto base station 1 is in a state where the reception sensitivity is set to “S0” in order to withstand uplink interference or to narrow the radius of the uplink area.

  Further, it is assumed that the femto base station 1 manages registered mobile devices in advance. It is assumed that the femto base station 1 can set the reception sensitivity to any of “S0”, “S1”, “S2”... “Sn”.

  Further, the transmission power of the paging signal corresponding to each reception sensitivity is a value that allows the paging signal to reach the area range when each reception sensitivity is applied.

  In step S201, the femto base station 1 determines whether or not uplink communication from the registered mobile device is interrupted for a predetermined period. If it is determined that the operation has been interrupted, the operation proceeds to step S202. If it is determined that the operation has not been interrupted, the operation repeats step S201.

  In step S202, the femto base station 1 sets the reception sensitivity “Sk” to the current reception sensitivity “Sm”.

  In step S203, the femto base station 1 determines whether or not there is room for increasing the reception sensitivity, that is, whether or not “k” ≧ “n”. If it is determined that there is room (“k” <“n”), the operation proceeds to step S203, and if it is determined that there is no room (“km” ≧ “n”), Operation proceeds to step S208.

  In step S204, the femto base station 1 increases the reception sensitivity ("k" is increased by "1" "), and in step S205, the transmission power" A paging signal is transmitted at “Pk”.

  In step S206, the femto base station 1 determines whether or not a response to the paging signal from the registered mobile device has been received. When it is determined that it has been received, the operation proceeds to step S207, and when it is determined that it has not been received, the operation returns to step S203.

  In step S207, the femto base station 1 determines that the signal from the registered mobile station existing in the service area cannot be detected with the current reception sensitivity, and sets the reception sensitivity “Sk” increased in step S204. .

  On the other hand, when “k” becomes “n”, the femto base station 1 determines that there is no registered mobile device in the service area or there is no room for increasing the reception sensitivity in the first place, and in step S208 The reception sensitivity is not changed from “Sm”, and a timer is set in step S209.

  According to the base station according to the first modification, it is possible to automatically set the optimum parameters for the base station based on the reception sensitivity and transmission power when the registered mobile station responds to the above call.

  In the first modification, an example in which there is one registered mobile device has been described. However, even if there are a plurality of registered mobile devices, the same operation is performed.

  In such a case, the femto base station 1 may determine the reception sensitivity when receiving a response from one registered mobile device among a plurality of registered mobile devices, or the registered mobile device set as a reference. The reception sensitivity may be determined when a response is received from.

  Further, the femto base station 1 is configured to continue to increase “m” until it receives responses from all registered mobile devices or until it receives responses from a predetermined number of registered mobile devices. Also good.

  Here, the femto base station 1 uses a timer when the reception sensitivity is changed and called, but the reception sensitivity may be changed and called at a predetermined period, or at a timing notified from the network. The reception sensitivity may be changed and called.

  The characteristics of the present embodiment described above may be expressed as follows.

  A first feature of the present embodiment is a base station (femto base station) 1, which is a registered mobile station management unit (registered mobile station) configured to manage one or a plurality of mobile stations as registered mobile stations. Machine DB) 11, reception sensitivity control unit 14 configured to determine reception sensitivity for a signal transmitted via an uplink, and configured to transmit a paging signal to a registered mobile station. Paging signal transmission unit 17, and when a signal from the registered mobile device is not detected for a predetermined period, the reception sensitivity control unit 14 increases the reception sensitivity, and the paging signal transmission unit 17 The reception sensitivity control unit 14 is configured to determine the reception sensitivity based on the presence / absence of a response to the paging signal from the registered mobile device. It is the gist of.

  In the first feature of this embodiment, when a signal from a registered mobile device is not detected for a predetermined period, the reception sensitivity control unit 14 increases the reception sensitivity, and the paging signal transmission unit 17 The paging signal may be transmitted with transmission power corresponding to the increased reception sensitivity.

  In the first feature of the present embodiment, a transmission power control unit 19 configured to determine the transmission power of a signal to be transmitted via a downlink based on the presence / absence of a response to a paging signal from a registered mobile device. May further be provided.

  The second feature of the present embodiment is a mobile communication method, in which one or a plurality of mobile devices are managed as registered mobile devices, and a signal from the registered mobile device is detected for a predetermined period in the base station. If not, the reception sensitivity for the signal transmitted via the uplink is increased and the paging signal is transmitted to the registered mobile device, and the reception sensitivity is determined based on the presence or absence of a response to the paging signal from the registered mobile device. And a step C for determining the characteristics.

  In the second feature of the present embodiment, in step C, the paging signal may be transmitted to the registered mobile device with transmission power corresponding to the increased reception sensitivity.

  In the second feature of the present embodiment, the method may further include a step of determining transmission power of a signal to be transmitted via a downlink based on presence / absence of a response to a paging signal from a registered mobile device.

  The operation of the femto base station 1 described above may be implemented by hardware, may be implemented by a software module executed by a processor, or may be implemented by a combination of both.

  The software module includes a RAM (Random Access Memory), a flash memory, a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), an EEPROM (Electronically Erasable and Programmable ROM, a hard disk, a registerable ROM, a hard disk). Alternatively, it may be provided in a storage medium of an arbitrary format such as a CD-ROM.

  Such a storage medium is connected to the processor so that the processor can read and write information from and to the storage medium. Further, such a storage medium may be integrated in the processor. Such a storage medium and processor may be provided in the ASIC. Such an ASIC may be provided in the femto base station 1. Further, the storage medium and the processor may be provided in the femto base station 1 as a discrete component.

  Although the present invention has been described in detail using the above-described embodiments, it is obvious to those skilled in the art that the present invention is not limited to the embodiments described in this specification. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention.

FIG. 3 is a functional block diagram of a femto base station according to the first embodiment of the present invention. It is a flowchart which shows operation | movement of the femto base station which concerns on the 1st Embodiment of this invention. It is a functional block diagram of the femto base station which concerns on the modification 1 of this invention. It is a figure which shows an example of the comparison table memorize | stored by the femto base station which concerns on the modification 1 of this invention. It is a flowchart which shows operation | movement of the femto base station which concerns on the modification 1 of this invention.

Explanation of symbols

1 ... Femto base station 11 ... Registered mobile station DB
DESCRIPTION OF SYMBOLS 12 ... Reception part 13 ... Signal demodulation part 14 ... Reception sensitivity control part 15 ... Judgment part 16 ... Signal preparation part 17 ... Transmission part 18 ... Corresponding notation part 19 ... Transmission power control part

Claims (6)

A registered mobile device management unit configured to manage one or more mobile devices as registered mobile devices;
A reception sensitivity control unit configured to determine reception sensitivity for a signal transmitted via the uplink; and
A paging signal transmitter configured to transmit a paging signal to the registered mobile device;
When a signal from the registered mobile device is not detected for a predetermined period, the reception sensitivity control unit increases the reception sensitivity, and the paging signal transmission unit transmits a paging signal to the registered mobile device. Configured,
The base station, wherein the reception sensitivity control unit is configured to determine the reception sensitivity based on presence or absence of a response to the paging signal from the registered mobile device.   When the signal from the registered mobile device is not detected for the predetermined period, the reception sensitivity control unit increases the reception sensitivity, and the paging signal transmission unit increases the reception received from the registered mobile device. The base station according to claim 1, wherein the base station is configured to transmit a paging signal with transmission power corresponding to sensitivity.   A transmission power control unit configured to determine transmission power of a signal to be transmitted via a downlink based on presence / absence of a response to the paging signal from the registered mobile device. The base station according to claim 2. Process A for managing one or more mobile devices as registered mobile devices;
In the base station, when a signal from the registered mobile station is not detected for a predetermined period, the reception sensitivity for the signal transmitted via the uplink is increased and a paging signal is transmitted to the registered mobile station. ,
And C for determining the reception sensitivity based on whether or not there is a response to the paging signal from the registered mobile device.   5. The mobile communication method according to claim 4, wherein, in the step C, a paging signal is transmitted to the registered mobile device with transmission power corresponding to the increased reception sensitivity.   The mobile communication method according to claim 5, further comprising a step of determining a transmission power of a signal to be transmitted via a downlink based on presence / absence of a response to the paging signal from the registered mobile device.

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